6.24.2011

Fish, sharks, whales and other marine species are in imminent danger of an "unprecedented" and catastrophic extinction event at the hands of humankind, and are disappearing at a far faster rate than anyone had predicted, a study of the world's oceans has found.

Mass extinction of species will be "inevitable" if current trends continue, researchers said.

Overfishing, pollution, run-off of fertilisers from farming and the acidification of the seas caused by increasing carbon dioxide emissions are combining to put marine creatures in extreme danger, according to the report from the International Programme on the State of the Ocean (Ipso), prepared at the first international workshop to consider all of the cumulative stresses affecting the oceans at Oxford University.

The international panel of marine experts said there was a "high risk of entering a phase of extinction of marine species unprecedented in human history". They said the challenges facing the oceans created "the conditions associated with every previous major extinction of species in Earth's history".

"The findings are shocking," said Alex Rogers, scientific director of Ipso. "As we considered the cumulative effect of what humankind does to the ocean, the implications became far worse than we had individually realised. This is a very serious situation demanding unequivocal action at every level. We are looking at consequences for humankind that will impact in our lifetime, and worse, our children's and generations beyond that."

The flow of soil nutrients into the oceans is creating huge "dead zones", where anoxia - the absence of oxygen - and hypoxia - low oxygen levels - mean fish and other marine life are unable to survive there.

Hypoxia and anoxia, warming and acidification are factors present in every mass extinction event in the oceans over the Earth's history, according to scientific research. About 55m years ago, as much as half of some species of deep-sea creatures were wiped out when atmospheric changes created similar conditions.

In recent years, human effects on the oceans have increased significantly. Overfishing has cut some fish populations by more than 90%. Pollutants, including flame-retardant chemicals and detergents are absorbed into particles of plastic waste in the sea, which are then ingested by marine creatures. Millions of fish, birds and other forms of life are choked or suffer internal ruptures from ingesting plastic waste.

The scientists called on the United Nations and governments to bring in measures to conserve marine ecosystems. Dan Laffoley, of the International Union for the Conservation of Nature, said: "The world's leading experts on oceans are surprised by the rate and magnitude of changes we are seeing. The challenges for the future of the oceans are vast, but unlike previous generations we know what now needs to happen. The time to protect the blue heart of our planet is now, today and urgent".

About Oceanic DefenseWe are an international organization with members in over 60 countries, spanning 6 continents with 1 mission; healthy aquatic ecosystems free from human abuse and neglect. Oceanic Defense teaches people to protect our oceans by acting responsibly as consumers and by making smart decisions in our daily lives. Whether we are buying groceries, commuting to work, planning a vacation or advocating within our own communities; each action we take or decision we make either helps or hurts our oceans. We empower people to be part of the solution rather than part of the problem and work together to protect our blue planet.

6.10.2011

ScienceDaily — The present rate of greenhouse carbon dioxide emissions through fossil fuel burning is higher than that associated with an ancient episode of severe global warming, according to new research. The findings are published online this week by the journal Nature Geoscience.

Around 55.9 million years ago, Earth experienced a period of intense global warming known as the Palaeocene-Eocene Thermal Maximum (PETM), which lasted for around 170,000 years. During its main phase, average annual temperatures rose by around 5°C.

Scientists believe that the warming may have been initially triggered by an event such as the baking of organic-rich sediments by igneous activity that released the potent greenhouse gas, methane. This initial temperature increase warmed ocean bottom waters which allowed the break down of gas hydrates (clathrates), which are found under deep ocean sediments: this would have greatly amplified the initial warming by releasing even more vast volumes of methane. As the methane diffused from the seawater into the atmosphere it would have been oxidised to form carbon dioxide, another potent and longer-lived greenhouse gas.

Adam Charles and his PhD supervisor, Dr Ian Harding, both palaeoceanographers at the University of Southampton's School of Ocean and Earth Science (SOES) based at the National Oceanography Centre, Southampton, co-authored the report. Dr Harding said: "The PETM has been seen by many as a natural test bed for understanding modern human-made global warming, despite it not being a perfect analogy. However, the total amount of carbon released during this climatic perturbation and its rate of release have been unclear."

To help fill this gap in knowledge, the researchers measured carbon isotope ratios of marine organic matter preserved in sediments collected in Spitsbergen. The sedimentary section is important because it records the entirety of the PETM, from its initiation to through the recovery period, and as such is the most complete record of the warming event so far known in high northern latitudes.

Based on their carbon isotope measurements and computer simulations of Earth system, the researchers estimated that the rate of carbon emissions during the PETM peaked at between 300 million and 1,700 million metric tonnes per year, which is much slower than the present carbon emission rate.

"Our findings suggest that humankind may be causing atmospheric carbon dioxide to increase at rates never previously seen on Earth, which would suggest that current temperatures will potentially rise much faster than they did during the PETM," concluded Dr Harding.

This research was supported by The Worldwide Universities Network, Pennsylvania State University, and the US National Science Foundation.

About Oceanic DefenseWe are an international organization with members in over 60 countries, spanning 6 continents with 1 mission; healthy aquatic ecosystems free from human abuse and neglect. Oceanic Defense teaches people to protect our oceans by acting responsibly as consumers and by making smart decisions in our daily lives. Whether we are buying groceries, commuting to work, planning a vacation or advocating within our own communities; each action we take or decision we make either helps or hurts our oceans. We empower people to be part of the solution rather than part of the problem and work together to protect our blue planet.

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